Breast Cancer Ratios, 1986 to 1995

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Abstract

This map uses age-standardized ratios to further aid in regional comparisons. A value of 1.0 would indicate that the region rate is identical to the overall Canadian rate; a value greater than 1.0 would indicate that the rate for that region is higher than the Canadian rate; and, in turn, a ratio value less than 1.0 would indicate that the rate for the specific region is lower than the Canadian rate. Statistically low incidences of breast cancer are found in Newfoundland and Labrador, the territories, and northern areas of most provinces. Otherwise, each province has one or more pockets of significantly high breast cancer incidence. Health status refers to the state of health of a person or group, and measures causes of sickness and death. It can also include people’s assessment of their own health.

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Breast cancer incidence and mortality rates vary between the provinces and territories (Figure 1). The highest estimated incidence rate in 1999 was in Manitoba with Quebec having the lowest. Lung cancer incidence and mortality rate estimates for women are shown for comparison purposes.

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Figure 1. Provincial Breast and Lung Cancer Incidence and Mortality Rates, 1999

It is important to note that the numbers shown in this chart are estimates. Estimates are produced by the National Cancer Institute of Canada (1999) in order to assist with prevention and treatment program planning. Actual incidence and mortality rates usually differ little from estimates today because of the improved monitoring programs of the National Cancer Institute of Canada. However, the numbers shown should be used with caution especially when comparing provincial/territorial rates because these jurisdictions do have slightly different disease registration procedures.

The two maps of breast cancer incidence were derived from actual incidence values, not estimates. Both illustrate age-standardized incidence for the period 1986 to 1995 and should be read together as much as possible. The first shows age-standardized rates while the second is of classes of age-standardized ratios. (refer to: Standardization of Rates: A Methodological Note).

Perhaps the most striking spatial pattern that is shown on these maps is the statistically low incidence of breast cancer in Newfoundland and Labrador, the territories, and northern areas of most provinces. Otherwise, each province has one or more pockets of significantly high breast cancer incidence. These are often located in more southerly areas, but they do not seem to be restricted to either urban or rural areas alone.

The highest 1986 to 1995 breast cancer rates can be found in south-central and southern Manitoba where the age-standardized rates per 100 000 exceed 120. A similarly high rate can be found in Shelburne County, in southwestern Nova Scotia. Additional clusters of relatively high breast cancer incidence rates are located in southern Alberta and British Columbia. In Ontario, the highest rates can be found in the southwestern part of the province and in the Ottawa area.